Selective plating system

ABSTRACT

There is provided an apparatus for plating a portion of a work piece. The apparatus comprises a fixture having a cavity formed therein. The cavity is dimensioned to receive the portion of the work piece. An attaching means is provided for attaching the fixture to the work piece whereby a sealed chamber is formed between the fixture and the work piece. An inlet port in the fixture fluidly communicates with the sealed chamber. An outlet port in the fixture fluidly communicates with the sealed chamber. A circulation system fluidly connects to the inlet port and the outlet port and includes a source of a plating solution. The circulation system is operable to circulate a plating solution through the sealed chamber.

FIELD OF THE INVENTION

The present invention relates generally to plating, and moreparticularly, to selective plating of intricate surfaces on a workpiece.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for selectivelyplating intricate surfaces on a work piece. By way of example and notlimitation, the present invention finds advantageous application inselectively plating threaded surfaces on the end of a shaft, such asthreads on the end shaft for a jet engine. Heretofore, it was known toplate nickel onto the threaded ends of a jet engine shaft by maskingcertain portions of the shaft and suspending the shaft over a largeplating tank, and then dipping the end of the shaft in an electrolessnickel solution. Such a plating process requires large facilities,handling equipment and plating tanks. With such large handling equipmentand tanks, it is difficult to accurately control the plating conditionsand the properties of the metal plated on the surfaces of the shaft.

The present invention provides a system for encapsulating and platingthe end surfaces of a large, elongated work piece.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an apparatusfor plating a portion of a work piece. The apparatus comprises a fixturehaving a cavity formed therein. The cavity is dimensioned to receive theportion of the work piece. An attaching means is provided for attachingthe fixture to the work piece whereby a sealed chamber is formed betweenthe fixture and the work piece. An inlet port in the fixture fluidlycommunicates with the sealed chamber. An outlet port in the fixturefluidly communicates with the sealed chamber. A circulation systemfluidly connects to the inlet port and the outlet port and includes asource of a plating solution. The circulation system is operable tocirculate a plating solution through the sealed chamber.

In accordance with another aspect of the present invention, there isprovided a method of plating an end portion of an elongated work piececomprising the steps of:

(a) attaching a fixture to the end portion of a work piece to create asealed, fluid-tight chamber between the work piece and the fixture, thefixture having an inner surface with a profile conforming to an outersurface profile of the work piece, and further having fluid connectionmeans for fluidly connecting the fixture to a source of a platingsolution; and

(b) circulating the plating solution through the sealed chamber.

An advantage of the present invention is a method and apparatus forselectively plating sections of a work piece.

An advantage of the present invention is a system having a platingfixture for encapsulating the sections of the work piece to be plated.

An advantage of the present invention is a system as described abovewherein the encapsulating fixture includes means to facilitate cleaningof the areas to be plated.

Another advantage of the present invention is a method for encapsulatingand selectively plating select portions of a work piece wherein a testcoupon is simultaneously plated with the work piece.

Another advantage of the present invention is a system for selectivelyplating large, unwieldy parts that are difficult to plate in aconventional tank plating process.

A still further advantage of the present invention is a selectiveplating system that finds advantageous application in plating a smallnumber of parts.

A still further advantage of the present invention is a selectiveplating system wherein the plating parameters are more easily controlledas compared to a conventional tank plating process.

These and other advantages will become apparent from the followingdescription of a preferred embodiment taken together with theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangement ofparts, a preferred embodiment of which will be described in detail inthe specification and illustrated in the accompanying drawings whichform a part hereof, and wherein:

FIG. 1 is a perspective view showing a work piece and a plating fixtureillustrating a preferred embodiment of the invention;

FIG. 2 is a schematic view of a fluid circulation system mounted to theplating fixture shown in FIG. 1;

FIG. 3 is a microscopic image showing an electroless nickel (EN) coatingthickness in the valley of an internal thread;

FIG. 4 is a microscopic view showing an electroless nickel (EN) coatingthickness at the peak of a thread; and

FIG. 5 is a microscopic view showing an electroless nickel (EN) coatingthickness along the side of a thread.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings wherein the showings are for the purposeof illustrating a preferred embodiment of the invention only, and notfor the purpose of limiting same, the drawings show a plating system 10for selectively plating select areas of a large work piece 20. Thepresent invention is particularly applicable to plating screw threads onthe ends of a long shaft, such as, by way of example and not limitation,the internal and external threads on the ends of a jet engine shaft, andshall be described with particular reference thereto. It shall beunderstood, however, that the present invention finds advantageousapplication in plating other types of work pieces. System 10 isgenerally comprised of a plating fixture 100, a fluid circulation system200 and a test strip container 300.

Referring now to FIG. 1, work piece 20 is a shaft having a tubular endportion 22. Tubular end portion 22 has a threaded outer section 24 and athreaded inner section 26. Tubular end portion 22 defines a cylindricalcavity 28 at the end of work piece 20. In another embodiment (notshown), work piece 20 is shaft wherein an opening extends a length ofthe shaft. In this embodiment, a second seal element (not shown) isdisposed in the opening to seal a portion of the opening to be platedfrom a remaining portion of the opening. In this respect, the sealelement and a portion of the opening in work piece 20 define cylindricalcavity 28.

Plating fixture 100 is comprised of a housing 110 that is generallycylindrical in shape and has an end wall 112 and a cylindrical side wall114 extending to one side thereof. Housing 110 is formed of anon-conductive material, such as, by way of example and not limitation,a polymer. End wall 112 defines a closed end of plating fixture 100.Side wall 114 defines a cylindrical opening 116 that is dimensioned toreceive end portion 22 of work piece 20. A cylindrical, center column122 is disposed within opening 116 defined by side wall 114. Centercolumn 122 is coaxial with the axis of side wall 114. Center column 122has an outer diameter that is smaller than cavity 28 in tubular endportion 22 of work piece 20. In this respect, an annular opening isdefined between side wall 114 and center column 122 of plating fixture100. The annular opening is dimensioned to receive end portion 22 ofwork piece 20, as illustrated in FIG. 2. A slot or groove 132, best seenin FIG. 2, is formed along the inner surface of side wall 114 near theend thereof. Slot 132 is dimensioned to receive an inflatable seal 134therein. An air line 136 extends through the side wall and communicateswith seal 134. Air line 136 is connectable to a source of air (notshown) to inflate seal 134.

As best seen in FIG. 2, an axially aligned opening 142 extends throughend wall 112 and through center column 122.

An electrode 144 is disposed along the outer surface of center column122. An electrode 146 is also provided along the inner surface of sidewall 114, as best seen in FIG. 2. In the embodiment shown, electrodes144, 146 are in the form of a metal screen. Leads 148 connected toelectrodes 144, 146 extend through fixture 100, and are connectable to apower source (not shown), to provide current to electrodes 144, 146. Alead 149 is connected to work piece 20. Lead 148 and lead 149 are shownin FIG. 2 connected to a positive (+) and a negative (−) terminal of thepower source, respectively, to illustrate opposite polarities and is notintended as a limitation of the invention disclosed herein.

Referring now to FIG. 2, fluid circulation system 200 is shown. In theembodiment shown, fluid circulation system 200 includes a waterreservoir 212, a cleaning fluid reservoir 214 and a plating solutionreservoir 216. As illustrated in the drawings, a heater 218 isassociated with plating solution reservoir 216 to heat the platingsolution therein. In accordance with one aspect of the presentinvention, each reservoir 212, 214, 216 is dimensioned to hold ten (10)gallons or less of fluid, and more preferably, five (5) gallons or lessof fluid, and more preferably, four (4) gallons or less of fluid. Waterreservoir 212 is connected to an input valve 222 by line 232. A pump 234is disposed in line 232 to convey water to input valve 222. Similarly,cleaning fluid reservoir 214 is connected to input valve 222 by a line242. A pump 244 is disposed in line 242 to convey cleaning fluid fromreservoir 214 to input valve 222. In accordance with one aspect of thepresent invention, reservoir 214 may be comprised of one or moreisolated chambers (not shown) that selectively fluidly communicate withline 242. It is contemplated that the isolated chambers may contain ade-smut solution, an etching solution, an activating solution or apre-plating solution. Plating solution reservoir 216 is connected toinput valve 222 by a line 252. A pump 254 in line 252 is provided toconvey the plating solution to input valve 222. Input valve 222 isconnected to a fixture feed line 262 that is connected to fixture 100.In the embodiment shown, fixture feed line 262 has a first branch feedline 262 a connected to opening 142 through center column 122, and asecond branch feed line 262 b connected to a fitting 264 through sidewall 114. A second fitting 266 in side wall 114 is connected to a returnline 272 that connects to an output valve 274. Output valve 274 hasthree (3) return lines 282, 284, 286 connected respectively to waterreservoir 212, cleaning fluid reservoir 214 and plating solutionreservoir 216. In accordance with one aspect of the present invention,reservoir 214 may be composed of one or more isolated chambers (notshown) that selectively fluidly communicate with return line 284. Inaccordance with another aspect of the present invention, output valve274 has a fourth return line (not shown) connected to a waste container(not shown). In this respect, the fourth return line fluidly connectsfluid circulation system 200 to the waste container to allow for theremoval of waste generated therein.

Container 300 is disposed within fixture feed line 262. Container 300defines a test chamber 312 dimensioned to receive test strips 314.

System 10 shall now be further described with respect to a process forelectroless plating of nickel (Ni) on the threaded sections of workpiece 20. Portions of work piece 20 that are not to be plated are maskedby conventionally known materials to prevent metal from plating thereon.The areas to be plated, i.e., the threaded sections, are then cleanedwith a conventionally known cleaning material, such as acetone, toremove grease or organic materials therefrom. It is also contemplatedthat cleaning of work piece 20 may involve the use of electrodes 144,146 and other solutions to aid in the cleaning process. Plating fixture100 is then attached to the end of work piece 20. Fixture 100 isdimensioned such that a predetermined gap is formed between the innersurface of side wall 114 and work piece 20 and between central column122 and work piece 20, as shown in FIG. 2. Air is provided through airline 136 to inflate seal 134, thereby forming an enclosed chamber aroundtubular end portion 22 of work piece 20. Work piece 20 is thusencapsulated within fixture 100.

In one embodiment of the invention, a test strip 314 (or strips) isinserted into test chamber 312 of container 300, prior to initiating aplating process. In this embodiment, test strip 314 is attached to lead149 and test container 300 is attached to lead 148. In anotherembodiment (not shown), test strip 314 is inserted into cavity 28 ofwork piece 20. In this embodiment, test strip 314 is electricallygrounded to work piece 20. Test strip(s) 314 are formed of the samematerial that forms the threaded surfaces of work piece 20 to be plated.

With plating fixture 100 in place and securely sealed onto the end ofwork piece 20, work piece 20 undergoes preparatory procedures prior toplating. Such procedures are generally conventionally known. Cleaningfluid may also be applied to the encapsulated region to clean andprepare the threaded surfaces of work piece 20 for plating. Followingany cleaning process, work piece 20 is preferably rinsed with water.

Once the preparatory procedures have been completed, input valve 222 andoutput valve 274 are moved to positions to allow the nickel platingsolution to be circulated through the chamber defined in fixture 100.The nickel plating solution has preferably been heated by heater 218 toa desired temperature to facilitate plating. The nickel plating solutionis continuously conveyed through the plating chamber for a predeterminedperiod of time. During this predetermined period of time, the nickelplating solution is constantly replenished to maintain a desiredchemistry for plating the internal and external threads of work piece20. After the plating has been completed, input valve 222 and outputvalve 274 move to a position to allow rinse water to flow through theplating chamber so as to remove any residual plating solution therefrom.Air seal 134 is then deflated and plating fixture 100 is removed fromwork piece 20.

As will be appreciated from a description of the foregoing, whilevarious solutions are being conveyed through plating fixture 100, suchsolutions also flow through test container 300, thereby exposing teststrips 314 to the same processes and chemistries experienced by thesurface of work piece 20. Since test strips 314 are formed of the samematerial as the surfaces of work piece 20 to be plated, test strips 314provide a method of verifying the plating process. Test strips 314 canthus be examined without requiring that the actual surface of work piece20 be tested in any way. Test strips 314 in test container 300 areanalyzed to determine an adhesion characteristics and a thickness of theelectroless nickel plating.

The foregoing process is used to apply electroless nickel onto selectsections of work piece 20. The foregoing procedure may find advantageousapplication in numerous types of electroless plating processes.

In one application of the present invention, the foregoing process andapparatus are used to apply an electroless nickel onto a shaft formed ofMaraging 250. Maraging 250 is an 18% nickel, cobalt strengthened steel(C-type), with excellent mechanical properties, workability and heattreatment characteristics. In the application described below, Atotech2810-1 NICHEM EN is used as the electroless nickel solution. Theelectroless nickel solution is heated to about 200° F. by heater 218 intank 216. While the electroless solution is heating, portions of workpiece 20 that are not to be plated are masked using aluminum tape, andother conventionally known masking materials. Test strips 314 aremounted in cavity 28 of work piece 20 and electrically grounded to workpiece 20. Work piece 20 is then cleaned using acetone and platingfixture 100 is attached to work piece 20 as described above.

Following the attachment of fixture 100 to work piece 20, the followingpreparatory procedure is performed on work piece 20 and test strips 314.A cleaning solution, is circulated through the chamber defined inplating fixture 100 for about 30 seconds while simultaneously applyingabout 10 volts to electrodes 144, 146 and work piece 20. Cleaningsolution is formulated to clean portions of work piece 20 and teststrips 314 that are to be plated. In present application, cleaningsolution is SIFCO ASC ElectroCleaning solution Code 1010/4100. Ade-ionized water solution is then circulated through the chamber definedin plating fixture 100. An etching solution is circulated through thechamber for about 15 seconds while simultaneously apply a reversedvoltage of between about 10 volts to about 13 volts to electrodes 144,146 and work piece 20. The etching solution etches portions of workpiece 20 and test strips 314 that are to be plated. In the presentapplication, the etching solution is SIFCO Etching Solution #1024.De-ionized water is then circulated through the chamber to rinse workpiece 20 and test strips 314. Next, a de-smut solution is circulatedthrough the chamber in fixture 100 for about 30 seconds whilesimultaneously applying between about 15 volts to about 20 volts toelectrodes 144, 146 and work piece 20. The de-smut solution de-smuts,i.e. removes smut, from portion of work piece 20 and test strips 314 tobe plated. In the present application, the de-smut solution is SIFCODesmut Solution #1023. Work piece 20 and test strips 314 are then rinsedagain with de-ionized water. Next, an activation solution is thencirculated through the chamber in fixture 100 for about one minute whileapplying a reversed voltage of about 15 volts to electrodes 144, 146 andwork piece 20. The activation solution activates portions of work piece20 and test strips 314 to be plated. In the present application, theactivation solution is SIFCO Solution 1024. Work piece 20 and teststrips 314 are then wetted with a pre-plating solution. In the presentapplication, the pre-plating solution is SIFCO Solution 5630. After workpiece 20 and test strip 314 are rinsed with the pre-plating solution, avoltage of about 6 volts is applied to electrodes 144, 146 and workpiece 20 for about one minute while the pre-plating solution continuesto circulate through the chamber in fixture 100. The pre-platingsolution pre-plates portions of work piece 20 and test strips 314 thatare to be plated. Work piece 20 and test strips 314 are then rinsed withde-ionized water.

Following the preparatory procedure described above, the electrolessnickel solution is circulated through the chamber in fixture 100 forabout 65 minutes to plate work piece 20 and test strips 314. After theplating process, fixture 100 is removed from work piece 20 and workpiece 20 and test strips 314 are rinsed and air dried. Test strips 314are then examined to characterize the electroless nickel platingrelative to adhesion, coating thickness, composition, internal stress,corrosion resistance and hydrogen embrittlement, as described below. Thetest strips 314 are made of various materials and have various featuresformed therein, depending on the characteristic of the electrolessnickel plating to be examined. For example, in one embodiment, a teststrip 314 made of carbon steel and a test strip 314 made of Maraging 250are plated to examine adhesion. In another embodiment, test strips 314are formed to have grooves and notches along the surface thereof tosimulate internal and external threads, wherein a coating thickness onthe groves or notches is indicative of the coating on the internal andexternal threads of work piece 20.

To determine the adhesion characteristics of electroless nickel platedon test strips 314, an adhesion test is conducted using a 180° bendmethod specified by ASTM E 290-97a (Standard test methods for bendingtesting of material for ductility). Two test strips 314 are used in theadhesion test. One test strip 314 is made of carbon steel and the othertest strip 314 is made of Maraging 250, the same material as work piece20. Both test strips 314 are bent rapidly at room temperature throughabout 180° around a diameter equal to a nominal thickness of test strip314. The test strips 314 are then observed under a microscope using 8Xmagnification. Flaking or peel-off of the electroless nickel plating isnot observed for test strip 314 made of steel, although the electrolessnickel plating is cracked. Flaking and peel-off are occasionallyobserved on test strip 314 made of Maraging 250.

After a bending test, described above, bent test strips 314 are mountedand polished following a standard metallographic procedure. The adhesionof the electroless nickel plating on an outer/tension side and on aninner/compression side of bent test strip 314 are analyzed. It isdetermined that some portions of test strip 314 have separated. Althoughoccasional flaking/peel-off occurs when the substrate separates undersevere bending, the adhesion of the electroless nickel plating isconsidered acceptable.

An adhesion referee test is conducted per 3.4.3.1 of AMS 2405c. A steeltest strip 314 is plated with work piece 20 in plating fixture 100. Teststrip 314 is then heated to about 700° F. for about 24 hours and then toabout 1000° F. for about one (1) hour in air using a Blue M^(®) furnace.A color change of the electroless nickel plating on test strip 314 isobserved after heating, but no blistering or cracking is observed.

Based on the results above, it is concluded that the electroless nickelplating shows good adhesion to test strip 314 and thereby passes theadhesion referee test.

A coating thickness of the electroless nickel plating is determined byusing a test strip 314 having internal and external threads. The teststrip 314 is mounted and polished. The electroless nickel platingthickness is measured using a Nikon® microscope with Buehler Omnimet^(®)image analyzer software. The microscope and analyzer software are usedto measure the electroless nickel plating thickness in a valley of athread, and on a peak of a thread, best seen in FIGS. 3 and 4respectively. The microscope and analyzer software are also used tomeasure the electroless nickel plating thickness distribution over athread, best seen in FIG. 5.

As seen in FIGS. 3-5, the electroless nickel plating thickness isuniform over the threads and measures no more than about 0.0008″ at thevalley of a thread.

A composition of the electroless nickel plating is measured using twoelectroless nickel plated test strips 314. The test strips are analyzedusing an Energy Dispersive Spectroscopy following ASTM E 1508-98. Theresults are shown in Table 1. TABLE 1 Results of composition analysisTest # Phosphorus Nickel 1 4.5% 95.5% 2 4.8% 95.2%

The composition of the electroless nickel plating is mainly determinedby the electroless nickel solution. In a preferred embodiment, theelectroless nickel solution is a low phosphorus solution, which givesfrom about 3% to about 5% phosphorous content in the coating.

As required by AMS 2405c (Electroless Nickel Plating Low Phosphorus),the phosphorus content in the electroless nickel plating is less than8%.

An internal stress test is conducted on the electroless nickel platingto perform an internal stress test, a test strip 314, made of a piece ofcopper foil with thickness of about 0.0032″ is used. The electrolessnickel plating having a thickness of about 0.0012,″ as measured by aMitutoyo^(®) digital micrometer, is applied to copper foil test strip314 The copper foil test strip 314 does not show any irregular warpafter electroless nickel plating. During one subsequent internal stresstest, test strip 314 is a stainless steel foil. The test strip 314 isplated with electroless nickel and then the electroless nickel platingis removed from the stainless steel test strip 314. The electrolessnickel plating shows no irregular warp.

Based on the internal stress test above, the electroless nickel platinghas a very low internal stress or is free of internal stresses.

A corrosion test is performed on a test strip 314 made of Maraging 250.The Maraging 250 test strip 314 is plated with electroless nickel thenheat treated to about 375° F. for about eight (8). The Maraging 250 teststrip 314 is then put into a salt fog chamber for about 48 hours. Thecorrosion test follows ASTM B 117-03. At a conclusion of the corrosiontest, the Maraging 250 test strip 314 shows no sign of coupon corrosion.

Based on the corrosion test above, the electroless nickel plating meetsa corrosion resistance requirement of AMS 2405c.

A hydrogen embrittlement test is next performed on four (4) test strips314. Test strips 314 are notched bars supplied by a manufacturer of workpiece 20. The four test strips 314 are electroless nickel plated andthen stored for about twelve (12) hours. The test strips 314 are thenheated to about 375° F. for about eight (8) hours. The test strips 314are tested for hydrogen embrittlement per ASTM F 519-97 (Standard TestMethod for Mechanical Hydrogen Embrittlement Evaluation of PlatingProcesses and Services Environments). The test strips 314 are subjectedto about 200 hours of sustained tensile load at about 75% (7442 LBS) anultimate tensile strength (about 9923 LBS). No hydrogen embrittlementfailures of test strip 314 are recorded. The test strips are visuallyinspected after the test and no embrittlement cracks are noted in thetest strips 314.

Based on the hydrogen embrittlement test above, the electroless nickelplating produced by the present invention conforms ASTM F 519.

The foregoing description is a specific embodiment of the presentinvention. It should be appreciated that this embodiment is describedfor purposes of illustration only, and that numerous alterations andmodifications may be practiced by those skilled in the art withoutdeparting from the spirit and scope of the invention.

The present invention thus provides a method and apparatus for theselective plating of surfaces. By encapsulating only a small portion ofthe work piece having the surfaces to be plated therein, the presentmethod and apparatus allows for use of smaller volumes of solution. Thevolume of solution necessary is generally related to the part size andthe thickness of the plating. One benefit of using smaller volumes ofsolution is the ability to more easily and quickly adjust and maintaindesired chemical and pH levels. In addition, by moving a smaller volumeof solution over the work piece surface, the temperature of the workpiece can be more easily maintained and depletion of the ions from thesolution, particularly in the vicinity of the work piece, can beregulated.

Another aspect of the present invention is the provision of electrodesalong the inner surface of plating fixture 100. While the foregoingembodiment has been described with respect to an electroless nickelplating process, as will be appreciated by those skilled in the art, anelectro-deposition process can be performed using plating fixture 100.

It is intended that all such modifications and alterations be includedinsofar as they come within the scope of the invention as claimed or theequivalents thereof.

1. An apparatus for plating a portion of a work piece, said apparatuscomprised of: a fixture having a cavity formed therein, said cavitydimensioned to receive said portion of said work piece; attaching meansfor attaching said fixture to said work piece whereby a sealed chamberis formed between said fixture and said work piece; an inlet port insaid fixture fluidly communicating with said sealed chamber; an outletport in said fixture fluidly communicating with said sealed chamber; anda circulation system fluidly connected to said inlet port and saidoutlet port, said circulation system including a source of a platingsolution and being operable to circulate said plating solution throughsaid sealed chamber.
 2. An apparatus as defined in claim 1, wherein saidportion is an end of an elongated work piece.
 3. An apparatus as definedin claim 2, wherein said attaching means is an inflatable seal disposedbetween said fixture and said work.
 4. An apparatus as defined in claim1, wherein said work piece is a cylindrical shaft.
 5. An apparatus asdefined in claim 4, wherein said attaching means is an inflatable sealdisposed between an inner wall of said fixture and an outer surface ofsaid work piece.
 6. An apparatus as defined in claim 1, wherein saidfixture includes: an inner surface having an inner profile conforming toan outer surface profile of said portion of said work piece, said innersurface being a fixed distance from said portion of said work piece todefine a gap between said fixture and said work piece.
 7. An apparatusas defined in claim 6, further comprising: an electrode disposed in saidgap a fixed distance from said portion of said work piece; andelectrical means for creating an electrical potential between saidelectrode and said work piece.
 8. An apparatus as defined in claim 1,further comprising: a cavity formed in said circulation system, saidcontainer having a cavity formed therein fluidly communicating with saidcirculation system; and a test strip disposed within said cavity of saidcontainer, said test strip made of a same material as said work piece,said test strip having a surface to be plated.
 9. An apparatus asdefined in claim 1, wherein said circulation system is comprised of: atank containing a plating solution; a circulation line connecting saidtank to said inlet port and to said outlet port to form a closed loop;heating means for heating said plating solution to a predeterminedtemperature; and a pump disposed in said circulation system forcirculating said plating solution along said closed loop and throughsaid sealed chamber.
 10. An apparatus as defined in claim 9, whereinsaid heating means is a heater disposed in said tank.
 11. An apparatusas defined in claim 1, wherein said circulation system includes: a firsttank fluidly communicating with said sealed chamber, said first tankcontaining said plating solution; a second tank fluidly communicatingwith said sealed chamber, said second tank containing a cleaningsolution; and a third tank fluidly communicating with said sealedchamber, said third tank containing a rinsing solution.
 12. An apparatusas defined in claim 11, further comprising a first pump disposed in saidcirculation system for circulating said plating solution in said firsttank to said sealed chamber; a second pump disposed in said circulationsystem for circulating said cleaning solution in said second tank tosaid sealed chamber; and a third pump disposed in said third path forcirculating said rinse solution in said third tank to said sealedchamber.
 13. An apparatus as defined in claim 11, wherein saidcirculation system further comprises: a first valve disposed in saidcirculation system between said fixture and said first tank, said secondtank and said third tank, said first valve selectively controlling flowfrom said sealed chamber to said first tank, said second tank and saidthird tank; and a second valve disposed in said circulation systembetween said fixture and said first tank, said second tank and saidthird tank, said first valve selectively controlling flow from saidfirst tank, said second tank and said third tank to said sealed chamber.14. A method of plating an end portion of an elongated work piececomprising the steps of: (a) attaching a fixture to said end portion ofa work piece to create a sealed, fluid-tight chamber between said workpiece and said fixture, said fixture having an inner surface with aprofile conforming to an outer surface profile of said work piece, andfurther having fluid connection means for fluidly connecting saidfixture to a source of a plating solution; and (b) circulating saidplating solution through said sealed chamber.
 15. In a method as definedin claim 14, further comprising: a cleaning step of circulating acleaning solution through said sealed chamber and circulating a rinsingsolution through said sealed chamber prior to said step (b) ofcirculating.
 16. A method as defined in claim 14, further comprising: anetching step of simultaneously circulating an etching solution throughsaid sealed chamber and energizing an electrode disposed in said sealedchamber a fixed distance from said portion of said work piece prior tosaid step (b) of circulating.
 17. A method as defined in claim 14,further comprising: a de-smuting step of simultaneously circulating ade-smut solution through said sealed chamber and energizing an electrodedisposed in said sealed chamber a fixed distance from said portion ofsaid work piece prior to said step (b) of circulating.
 18. A method asdefined in claim 14, further comprising: an activation step ofsimultaneously circulating an activation solution through said sealedchamber and energizing an electrode disposed in said sealed chamber afixed distance from said portion of said work piece prior to said step(b) of circulating.
 19. A method as defined in claim 14, furthercomprising: a pre-plating step of simultaneously circulating apre-plating solution through said sealed chamber and energizing anelectrode disposed in said sealed chamber a fixed distance from saidportion of said work piece prior to said step (b) of circulating.